A member of an online community to which I belong posed this very interesting question to me on a psychology thread: Could fear be the origin of the entire spectrum of human emotion?
Very thought provoking question. Fear is certainly what we consider a primary human emotion (among other emotions, e.g. happiness, anger, and sadness). Thinking about fear as the first emotion to appear in living things evolutionarily though is interesting.
[When we talk about origins, there are two types: a single person's individual origins and evolutionary origins. Being that each person comes into the world with a complex nervous system, it doesn't make sense to think of fear as being each individual's ultimate primary emotion. Considering this question in an evolutionary sense is far more interesting.]
In an evolutionary sense, fear is - of course - vital. Fear as a threat detection and deflection system certainly seems to rank #1 in terms of importance.
In fact, earlier in the thread in which this blog post originated, I discussed Kandel's Nobel Peace Prize winning work on the "memory" of slugs. The response that sea slugs can "remember" to recoil after being pinched in the gill is certainly very interesting. While this borders on what may seem like a classical conditioning response, there could be the beginnings of fear like responses here. [In terms of fear and how it relates to memory, it may be interesting to note here that fear evokes a release of calcium in the brain that leads to highly ingrained encoding of information.]
Although Freud might have said that sex drive is more primary, I'm not so sure. Perhaps fear responses were actually first to develop evolutionarily and reproduction urges (which aren't really emotions anyhow) came about later. But sex, and it's relation to love, seem way more advanced than fear. As far as a sea slugs is concerned - it is a hermaphrodite so a drive to (at least) seek out sex probably isn't that developed.
Along with sex, maybe other positive emotions simply aren't as necessary from an evolutionary standpoint. In fact, maybe emotions from being comforted and soothed developed after fear as a way to reduce and control it. Paul Gilbert Ph.D. talks about the importance of the physiological Soothing and Contentment System - but soothing from what? My guess is anxiety / fear - which was on the scene first.
Along with positive feelings of being soothed, exhilaration or happiness might also be linked to fear. Just think about the last time you were on a rollercoaster. Since the feeling of fear seems more important than exhilaration, it may be the case that feeling exhilaration developed out of the fear system.
[Hm - just had a thought about bipolar disorder and the sadness and happiness responses being a result of a dysregulation of anxiety systems, one that leads to prolonged depression and the other that leads to constant exhilaration. Anyhow - back to the original question.]
After talking about some positive feelings and the link to anxiety, let's consider anger. We know that someone's "threat detection system" is activated when they're angry. In other words, they may feel anxiety, and anger is the motivator to act. Therefore, the argument could be made that anxiety is first and anger has developed secondarily in the more advanced fight or flight system. We now have two options in response to anxiety: fight (anger) or flee.
Ok, now let's shift from talking about fear arising first on the evolution scene, to fear underlying our everyday experiences now.
For fun, let's consider the link between fear and depression as a psychiatric disorder. When first reading this question, my mind immediately jumped to the link between these two things. Prolonged fear / stress releases enormous amounts of cortisol, which impairs the functioning of the brain (for the scientifically curious - along the Hypothalamic Pituitary Adrenal axis) and leads to depression. Therefore, prolonged fear / stress is experienced first, and we think this is one route to depression.
Now, I realize depression is a psychiatric disorder linked to sadness, but it is not sadness itself. Therefore, saying fear always prompts sadness would not be a logical inference per se. On the other hand, these symptoms may be intimately linked whereas fear sometimes comes first. For instance, one may experiencing horror at the loss of a loved one first, and then deep sorrow. Typically people don't go straight to sad. There is usually shock (perhaps an anxiety response) and then sadness kind of sinks in either seconds, minutes, hours, or days later.
Flipping back into evolutionary terms, it seems that sadness is quite an advanced emotion compared to fear. While I can imagine an insect having a developed reactionary response with the rudimentary beginnings of a fear system, I can't necessarily picture a sorrow system.
In short, I think the case can be made that fear (as it stems from stimulus / threat detection) may be the ultimate primary emotion.